HR3C奥氏体耐热钢焊接接头中的析出相

Precipitates in Welded Joint of HR3C Austenitic Heat Resistant Steel

综述了高温长期暴露后HR3C钢焊接接头中的析出相及其影响。结果表明,HR3C钢接头显微组织主要为奥氏体+析出相(含晶界和晶内),接头各区析出相的种类、形态、数量和分布不尽相同。在高温运行期间,晶界处大量碳元素与铬、铁、钼、镍等元素化合,形成所谓M_(23)C_(6)型碳化物;纯奥氏体中直接析出σ相非常缓慢。奥氏体钢接头中大规模原子位移,如再结晶前沿的推进或变形,会大大加速σ相转变。高温长期暴露后接头的低塑性与析出相(尤指σ相)之间存在相关性;接头中产生的应力和塑性应变会进一步加速晶界σ相的析出,致使接头的延展性变差而脆化。

The precipitates in welded joint of HR3C steel after long-term exposure to high temperature and their effects were reviewed.The results show that the microstructure of HR3C steel joint is mainly austenite+precipitated phase(including grain boundary and intragranular).The type,morphology,quantity and distribution of precipitates in each area of the joint are different.During high temperature operation,a large number of carbon elements at the grain boundary combine with chromium,iron,molybdenum,nickel and other elements form the so-called M_(23)C_(6) carbide.Direct precipitation in pure austeniteσphase is very slow.The large-scale atomic displacement in austenitic steel joint,such as the advance or deformation of recrystallization front,will be greatly acceleratedσphase transition.There is correlation between the low plasticity and precipitates of joints after long-term exposure to high temperature(especiallyσphase).The stress and plastic strain generated in the joint will further accelerate the grain boundaryσphase,which leads to poor ductility and embrittlement of the joint.